FLUX 3 Klein: The Open-Weights FLUX 3 Model, Explained
FLUX 3 Klein is the small, open member of the FLUX 3 Image family: 5.6B parameters, up to 10 reference images, bounding-box layout and native 4K, from $0.009 an image. Here is what FLUX 3 Klein does, what it costs, and where to run it.
- FLUX 3 Klein: 5.6B open weights
- 10 reference images
- 768px to 4K
FLUX AI Image Generator
A sample prompt that suits FLUX 3 Klein is filled in, so you can generate right away, or switch to Image to Image to edit a photo.
FLUX 3 Klein API access is still rolling out to our provider. This generator runs on Flux 2 Pro today and switches to FLUX 3 Klein as soon as it is available.
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What Is FLUX 3 Klein?
FLUX 3 Klein (officially FLUX 3 Image Klein) is the open-weights image model in Black Forest Labs' FLUX 3 family. It arrived on October 15, 2026, two weeks after the full FLUX 3 Image model, and keeps that model's headline tricks at a fraction of the size and price.
You can download FLUX 3 Klein from Hugging Face and run it in ComfyUI or your own pipeline, or call it as flux-3-image-klein on the BFL API, fal, Replicate or OpenRouter.
- Released
- Oct 15, 2026
- Parameters
- 5.6B
- Reference images
- Up to 10
- Max output
- Native 4K
- Text encoder
- Qwen3-VL-4B
- Weights
- Open (FLUX Kommunity License)
FLUX 3 Klein Features
What FLUX 3 Klein brings over earlier FLUX models, most of it shared with the full FLUX 3 Image model.
One model for every image job
FLUX 3 Klein handles text-to-image, instruction editing and multi-reference generation with the same weights. No separate edit model to switch to.
FLUX 3 Klein bounding boxes
Draw boxes to place elements, or to keep an edit inside one area. FLUX 3 Klein shares this control with the full FLUX 3 Image model.
Pixel-perfect editing
On the BFL API, FLUX 3 Klein's pixel restoration keeps unedited regions identical, so a fix stays a fix instead of a redraw.
Up to 10 FLUX 3 Klein references
Combine products, people and styles from up to ten images and keep them consistent in one FLUX 3 Klein output.
Text rendering and editing
FLUX 3 Klein writes legible text into images and can change text that's already there: labels, signs, poster titles.
Native 4K in FLUX 3 Klein
Resolution tiers from 768px to 4K, with wide and tall aspect ratios including 21:9.
How FLUX 3 Klein Bounding Boxes Work
Each box is four numbers, [top, left, bottom, right], on a 0–1000 grid, so [0, 0, 500, 500] is the top-left quarter of the image. Name what goes in each box in the prompt, and FLUX 3 Klein places it there. In an edit, a box limits the change to that region.
The boxes steer FLUX 3 Klein rather than cutting a hard mask, so keep the prompt and the boxes in agreement. Overlapping boxes and boxes smaller than a few percent of the frame are where results get loose.
headline [60, 100, 220, 900] "SUMMER SALE" in bold type product [300, 330, 860, 670] white sneaker, three-quarter view badge [700, 720, 900, 940] round "-30%" sticker
FLUX 3 Klein Price
Official BFL API prices for FLUX 3 Klein. Generation and editing cost the same at each tier.
For scale, the full FLUX 3 Image model is $0.048 at 1K, so FLUX 3 Klein runs at roughly a fifth of the price. On Bananaify, FLUX 3 Klein will run on the same credits as every other model, from a $19 pack, with the exact amount shown before you generate.
FLUX 3 Klein vs Other Image Models
How FLUX 3 Klein lines up against its big sibling, the previous Flux and Google's latest.
| FLUX 3 Klein | FLUX 3 Image | Flux 2 Pro | Nano Banana 2.1 | |
|---|---|---|---|---|
| Maker | Black Forest Labs | Black Forest Labs | Black Forest Labs | |
| Open weights | Yes, 5.6B | No | No (Pro) | No |
| Price at 1K | $0.009 | $0.048 | $0.025 | Not published |
| Reference images | 10 | 10 | 8 | 14 |
| Layout control | Bounding boxes | Bounding boxes | Prompt only | Masks |
| Max resolution | 4K | 4K | 2K | 4K |
FLUX 3 Klein vs FLUX 3 Klein Base
Black Forest Labs ships FLUX 3 Klein in two checkpoints. The distilled FLUX 3 Klein is tuned for low-step, low-latency generation and editing, and it is the one behind the API. FLUX 3 Klein Base is undistilled, slower, and meant for fine-tuning, LoRA training and research.
Where to run FLUX 3 Klein
Hosted: the BFL API (with prompt upsampling and pixel restoration), fal, Replicate, OpenRouter and NVIDIA NIM. Local: Hugging Face weights with FP8, INT8 and NVFP4 builds, plus native ComfyUI support. The FLUX Kommunity License allows free commercial use for smaller businesses; larger companies need a license from Black Forest Labs.
FLUX 3 Klein Prompt Ideas
Prompts that play to FLUX 3 Klein's strengths: real text, clean products and wide frames. Open one in the generator above.
FLUX 3 Klein poster with real text
Retro travel poster for Lisbon, yellow tram climbing a steep street, the word "LISBOA" in large cream letters at the top, flat screen-print style, warm limited palette
Use this prompt →FLUX 3 Klein product hero shot
A glass perfume bottle with amber liquid on a wet black stone, single dramatic side light, water droplets, dark moody background, luxury advertising photography
Use this prompt →FLUX 3 Klein packaging mockup
Front view of a kraft paper tea box labelled "Mountain Oolong" in elegant serif type, small hand-drawn leaf illustration, on a light oak table, soft daylight, product photo
Use this prompt →FLUX 3 Klein cinematic banner
Ultra-wide 21:9 cinematic shot of a lone cyclist on a coastal road at golden hour, cliffs and ocean, long shadows, film still, anamorphic look
Use this prompt →Bananaify Bananaify AI Plans
Professional image editing powered by Bananaify AI with unlimited revisions, priority access, and commercial rights for all Bananaify users.
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FLUX 3 Klein FAQ
FLUX 3 Klein price, license, boxes and availability.
FLUX 3 Klein (full name FLUX 3 Image Klein) is the open-weights member of Black Forest Labs' FLUX 3 Image family, released on October 15, 2026. One 5.6B-parameter model does text-to-image, instruction editing and multi-reference generation with up to 10 reference images, at up to native 4K.
The FLUX 3 Klein weights are free to download from Hugging Face under the FLUX Kommunity License, which allows free commercial use for smaller businesses; larger companies need a commercial license from Black Forest Labs. Hosted API calls are paid per image, from $0.008 at 768px to $0.036 at 4K.
On the BFL API, FLUX 3 Klein costs $0.008 at 768px, $0.009 at 1K, $0.011 at 1.5K, $0.014 at 2K and $0.036 at 4K, and editing costs the same as generation. That is roughly a fifth of the full FLUX 3 Image model at 1K.
Boxes let you tell FLUX 3 Klein where an element should go, or limit an edit to one region. Coordinates are written as [top, left, bottom, right] on a 0–1000 grid. They guide the model rather than acting as a hard mask, so keep the prompt consistent with the boxes.
The distilled FLUX 3 Klein checkpoint is tuned for fast, low-step generation and editing. FLUX 3 Klein Base is the undistilled model for fine-tuning, LoRA training and research. Most people generating images want the distilled one.
Not yet. FLUX 3 Klein API access is still rolling out to our provider, so the generator on this page runs Flux 2 Pro, the newest Flux model we can serve, and says so on the page. It switches to FLUX 3 Klein as soon as it's available, and the price per image is shown before you generate.
FLUX 3 Klein is the budget and self-hosting pick, with open weights, box-based layout and very low per-image prices. Nano Banana 2.1 is a closed Google model with search grounding and mask editing. Both run on Bananaify credits, so you can compare them side by side.
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